The goal of this proposal is to reduce the prevalence of chronic lung disease through smoking cesssation techniques introduced in an obstetric care setting. We shall study women attending the University Health Center for prenatal care who smoke one or more cigarettes per day. We shall examine the effectiveness of a smoking cessation program which includes: personal counseling at the first prenatal visit on individual risk to the mother and fetus, benefits of stopping smoking and specific ways to quite; maintanehane counseling concerning the social and emotional antecedents for relapse and the skills to cope with these; letters from the obstetrician reinforcing the messages of these counseling sessions; referral to self-help or group smoking cessation services; and home counseling on individual risk and quitting techniques. The major objective is to reduce the prevalence of cigarette smoking by 30% during the course of the pregnancy; a minor objective is to examine the outcome of the smoking cessation program in terms of the birthweight and respiratory morbidity of the offspring of the participants in the study. Specific aims of this proposal are to determine: the effectiveness of the smoking cessation counseling in comparison to the usual prenatal care; the extent to which motivations and intentions to quite smoking and success in attempts to quit smoking are increased by the counseling; the birthweight of the babies born to the participants in the study; and the respiratory mobidity which occurs among the infants during their first year of life. Smoking cessation counseling and referral to smoking cessation aids will be given at the first prenatal visit. Home counseling will be offered at the 20th week. Additional counseling will be given at the 36th week and at the first postpartum visit six weeks after delivery. Maintenance counseling will be provided at each prenatal visit to those women who stop smoking spontaneously because they are pregnant, as well as to women who stop smoking during the course of the program. Smoking behavior will be measured by self-report and by salivary thiocyanate concentration. The outcome of the program will be assessed at the time of delivery and one year later.